From f42d0fda0c67695db6bc704b04b7c10240805377 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Tue, 26 May 2026 15:35:06 -0400 Subject: [PATCH] SUNRPC: always drain cache_cleaner before destroying a cache_detail sunrpc_destroy_cache_detail() only cancels the global cache_cleaner delayed_work when cache_list is empty. During per-netns teardown cache_list is never empty because init_net's caches remain registered, so the cancel never fires. After unlink, the caller proceeds to cache_destroy_net() which kfrees the cache_detail while cache_clean() may still hold a dangling pointer to it. The result is a use-after-free: cache_dequeue() takes cd->queue_lock on freed memory, and cache_put() dereferences cd->cache_put as a function pointer from freed slab. Drop the list_empty guard so that cancel_delayed_work_sync() always runs, ensuring any in-flight cache_clean() completes before the cache_detail is freed. Re-arm the cleaner afterwards if other caches are still registered. Fixes: 820f9442e711 ("SUNRPC: split cache creation and PipeFS registration") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-6 Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20260526-cache_cleaner_vs_destroy_no_sync-v1-1-a707a6fcfd32@kernel.org Signed-off-by: Chuck Lever --- net/sunrpc/cache.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c index 391037f15292..1bc04109d213 100644 --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -430,10 +430,9 @@ void sunrpc_destroy_cache_detail(struct cache_detail *cd) list_del_init(&cd->others); spin_unlock(&cd->hash_lock); spin_unlock(&cache_list_lock); - if (list_empty(&cache_list)) { - /* module must be being unloaded so its safe to kill the worker */ - cancel_delayed_work_sync(&cache_cleaner); - } + cancel_delayed_work_sync(&cache_cleaner); + if (!list_empty(&cache_list)) + queue_delayed_work(system_power_efficient_wq, &cache_cleaner, 0); } EXPORT_SYMBOL_GPL(sunrpc_destroy_cache_detail);